What is the difference between an edge loop and an edge ring?
Edge Loop
An edge loop is a series of directly connected edges:

You can select an edge loop with AltRMB.
Edge Ring
An edge ring is a series of edges which are not directly connected, but share faces:

You can select an edge ring with CtrlAltRMB.

As a bonus, you can run the select edge loop or the select edge ring operator on every selected edge automatically by pressing Edge loop or Edge ring in 3D view &gt; Header &gt; Select.